Apparatus and method for reducing overall weight of rear differential cooling system

ABSTRACT

A method and apparatus are provided to reduce the overall weight of a rear differential cooling system of a motor vehicle. The apparatus includes a body panel system. That body panel system includes (a) a rear diffuser, having a front air inlet, (b) an underbody panel, overlying the rear diffuser as well as (c and d) first and second air tunnels formed between the rear diffuser and the underbody panel, and (e) a rear valance, including first and second vent openings for discharging air received from the first air tunnel. A heat exchanger is provided between the air tunnels and the vent openings. A related method for improving weight distribution and reducing overall weight of a rear differential cooling system is also provided.

This application is a division of U.S. patent application Ser. No.15/070,756 filed on 15 Mar. 2016, now U.S. Pat. No. 9,950,611.

TECHNICAL FIELD

This document relates generally to the motor vehicle equipment fieldand, more particularly, to an aerodynamic body panel system for managingthe air flow at a rear underside of a motor vehicle. A related method isalso disclosed.

BACKGROUND

In order to reduce lap times on a race track and increase tire grip, itis necessary to (a) add aerodynamic down force, (b) reduce power lossesdue to drag and (c) reduce and rebalance weight distribution.Simultaneously achieving these three goals is a very difficultengineering task.

In order to provide race track performance, most powertrain systemsrequire add-on coolers. Traditionally, rear axle or differential coolersare located toward the front of a motor vehicle. As a consequence, thesecoolers require long lines extending rearwardly from the coolers to therear differential. Such long lines require more fluid and larger pumpswhich add weight and deleteriously affect weight distribution. Further,such front-mounted coolers or heat exchangers often tend to have anegative impact on aerodynamic drag and often aerodynamic down force.

Ideally, coolers or heat exchangers for a rear axle or differentialshould be mounted at the rear of the motor vehicle thereby minimizingnegative impacts to aero drag and aero down force. However, providingair flow to a rear-mounted cooler or heat exchanger is very difficultunless it is mounted very low in the motor vehicle where it is at riskof impact from stones and debris. Further, it should be appreciated thatmany racetrack vehicles also serve a dual function as operatortransportation on public roads. Such low mounting of a cooler is also atrisk from speed bumps, steep driveway aprons and debris oftenencountered on public roads.

This document relates to a new and improved aerodynamic body panelsystem that manages the air stream at the rear end of the motor vehiclein a manner that enhances rear down force and minimizes or reducesaerodynamic drag. Additionally, the aerodynamic body panel system takesadvantage of the momentum of the passing air flow to feed air to a reardifferential heat exchanger that is mounted rearward in the vehiclebehind the rear axle to improve weight distribution and, therefore,motor vehicle handling.

Advantageously, the rear-mounted rear differential heat exchanger isalso physically protected thereby reducing the probability or risk ofimpact from stones, debris and other roadway obstructions.

SUMMARY

In accordance with the purposes and benefits described herein, a bodypanel system is provided for a motor vehicle. That body panel systemcomprises a rear diffuser including a front air inlet, an underbodypanel overlying the rear diffuser, a first air tunnel formed between therear diffuser and the underbody panel and a rear valance including afirst vent opening for discharging air received from the first airtunnel.

Alternatively, the body panel system may be described as comprising arear diffuser including a first air inlet and a second air inlet, anunderbody panel overlying the rear diffuser, first and second airtunnels formed between the rear diffuser and the underbody panel and arear valance including a first vent opening for discharging air receivedfrom the first air tunnel and the second air tunnel.

The first air tunnel may extend from a first air inlet to a first airtunnel outlet above the rear diffuser. Further, the second air tunnelmay extend from a second air inlet to a second air tunnel outlet abovethe rear diffuser.

The first air tunnel may have a first cross-sectional area A₁ at thefirst air inlet and a second cross-sectional area A₂ at the first airtunnel outlet where A₁<A₂. The second air tunnel may have a thirdcross-sectional area A₃ at the second air inlet and a fourthcross-sectional area A₄ at the second air tunnel outlet where A₃<A₄.

The rear valance may also include a second vent opening for dischargingair received from the first air tunnel and the second air tunnel.

The first vent opening and the second vent opening may be spaced fromthe first air tunnel outlet and the second air tunnel outlet. A heatexchanger may be provided between (a) the first vent opening and thesecond vent opening on one side and (b) the first air tunnel outlet andthe second air tunnel outlet on the opposite side. More specifically,the heat exchanger may be provided so as to extend over the first andsecond air tunnel outlets. The heat exchanger may provide cooling to arear differential of a motor vehicle.

In still other embodiments, the first vent opening may be aligned withthe first air tunnel outlet while the second vent opening may be alignedwith the second air tunnel outlet.

In accordance with an additional aspect, a method is provided forreducing the overall weight of a rear differential cooling system aswell as improving the weight distribution in a motor vehicle with afront mounted engine. That method includes the steps of: (a) mounting arear differential heat exchanger vehicle rearward of a rear axle of themotor vehicle, (b) directing air through an air inlet in a rear diffuserof the motor vehicle and then through the rear differential heatexchanger and (c) exhausting that air through a rear valence of themotor vehicle.

The method may also include the step of delivering the air from the airinlet to the rear differential heat exchanger by means of an air tunnel.Further the method may include increasing the cross sectional area ofthe air tunnel as the air tunnel approaches the rear differential heatexchanger.

In the following description, there are shown and described severalpreferred embodiments of the body panel system and related method. As itshould be realized, the body panel system and method are capable ofother, different embodiments and their several details are capable ofmodification in various, obvious aspects all without departing from thebody panel system and method as set forth and described in the followingclaims. Accordingly, the drawings and descriptions should be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated herein and forming a partof the specification, illustrate several aspects of the body panelsystem and together with the description serve to explain certainprinciples thereof. In the drawing figures:

FIG. 1 is a detailed perspective view illustrating the body panel, sansthe rear valance, for increasing down force, reducing aerodynamic dragand providing cooling air to a rear differential heat exchanger locatedvehicle rearward of the rear differential of the motor vehicle.

FIG. 2 is a rear perspective view of the body panel system showing therear valance, including the vent openings for discharging air, and therear diffuser including the first and second air inlets for drawing airinto the first and second air tunnels or ducts which direct air to therear differential heat exchanger.

FIG. 3 is a top plane view of the body panel system sans the rearvalance.

FIG. 4 is a schematic cross-sectional view of the body panel system sansthe rear valance.

FIG. 5 is a schematic cross-sectional view of the body panel systemillustrating how air is directed through a rear differential heatexchanger and then discharged from the motor vehicle by the body panelsystem.

Reference will now be made in detail to the present preferredembodiments of the body panel system, an example of which areillustrated in the accompanying drawing figures.

DETAILED DESCRIPTION

Reference is now made to FIGS. 1-5, illustrating the aerodynamic bodypanel system 10. That body panel system 10 includes a rear diffuser 12including a vortex generator 14, for producing down force, a first airinlet 16 and a second air inlet 18.

The body panel system 10 also includes an underbody panel 20 that issecured to the upper surface 22 of the rear diffuser 12. As bestillustrated in FIGS. 3-5, a first air tunnel or duct 24 is formedbetween the upper surface 22 of the rear diffuser 12 and the underbodypanel 20. Similarly, a second air tunnel or duct 26 is formed betweenthe upper surface 22 of the rear diffuser 12 and the underbody panel 20.As illustrated, the two air tunnels 24, 26 are provided side by side.

As best illustrated in FIG. 4, the first air tunnel 24 extends from thefirst air inlet 16 in the rear diffuser 12 to a first air tunnel outlet28 above the rear diffuser. As best illustrated in FIG. 5, the secondair tunnel 26 extends from the second air inlet 18 in the rear diffuserto a second air tunnel outlet 30 above the rear diffuser.

The first air tunnel 24 has a first cross-sectional area A₁ at the firstair inlet 16 and a second cross-sectional area A₂ at the first airtunnel outlet 28 where A₁<A₂. Thus, it should be appreciated that thecross-sectional area of the first air tunnel 24 increases as air movesfrom the first air inlet 16 toward the first air tunnel outlet 28.

The second air tunnel 26 has a third cross-sectional area A₃ at thesecond air inlet 18 and a fourth cross-sectional area A₄ at the secondair tunnel outlet 30 where A₃<A₄. Thus, the cross-sectional area of thesecond air tunnel increases as air moves from the second air inlet 18toward the second air tunnel outlet 30. The function of the change incross-sectional area will be described below.

The aerodynamic body panel system 10 also includes a rear valance 32.See FIGS. 2 and 5. In the illustrated embodiment, the rear valance 32includes a first vent opening 34 and a second vent opening 36 fordischarging air received from the first and second air tunnels 24, 26.As illustrated, the first and second vent openings 34, 36 are spacedfrom the first and second air tunnel outlets 28, 30. Further, the firstvent opening 34 in the rear valance 32 is aligned with the first airtunnel outlet 28 while the second vent opening 36 in the rear valance isaligned with the second air tunnel outlet 30.

A heat exchanger 38 may be provided in the space between (a) the firstand second vent openings 34, 36 on one side and the first and second airtunnel outlets 28, 30 on the other side. More specifically, that heatexchanger 38 may be provided over the first and second air tunneloutlets 28, 30. The heat exchanger 38 may be connected by feed lines 40to the rear differential 42 of the motor vehicle. See FIG. 1. In such anembodiment, the heat exchanger 38 provides a cooling function to therear differential 42. As illustrated, the heat exchanger 38 is providedmotor vehicle rearward of the rear differential 42 and rear axle (notshown) of the motor vehicle. As should be appreciated, the feed lines 40between the rear differential 42 and such a rearwardly located heatexchanger 38 are much shorter than they would otherwise be if the heatexchanger were located in the forward portion of the motor vehicle.Advantageously, weight savings result from the shorter feed lines 40,the need for less cooling fluid in the cooling system and the need for aless robust and more lightweight pump. Further, the relocation of theheat exchanger 38 from the front of the motor vehicle to the rear of themotor vehicle behind the rear differential 42 improves the weightdistribution of the motor vehicle thereby enhancing motor vehiclehandling.

As should be appreciated from reviewing FIGS. 3-5, a portion of the airflowing under the motor vehicle will be drawn upwardly into therespective first and second air tunnels 24, 26 through the first andsecond air inlets 16, 18 provided in the rear diffuser 12. That air willflow through the first and second air tunnels 24, 26 between the uppersurface 22 of the rear diffuser 12 and the underbody panel 20 toward thefirst and second air tunnel outlets 28, 30.

As previously noted, the first and second air tunnels 24, 26 bothprovide an increasing cross-sectional area as they extend between thefirst and second air inlets 16, 18 to the first and second air tunneloutlets 28, 30. As a consequence, air flowing through the first andsecond air tunnels 24, 26 toward the heat exchanger 38 decreases invelocity so as to flow more smoothly and with minimal turbulence throughthe heat exchanger 38 thereby cooling the coolant circulating in thefeed lines 40 between the heat exchanger 38 and the rear differential42. After the air passes through the heat exchanger 38 it is exhaustedfrom the motor vehicle through the first and second vent openings 34, 36provided in the rear valance 32.

Significantly, it should also be appreciated that the heat exchanger 38,provided at the end of the first and second air tunnels 24, 26 above therear diffuser 12 is well protected from rocks and road debris. Towardthis end the first and second air inlets 16, 18 may also be covered witha mesh if desired to prevent intrusion of objects into the first andsecond air tunnels 24, 26. Of course, it should also be appreciated thatthe rear diffuser 12 also protects the heat exchanger 38 from directcontact with speed bumps and steeply sloped driveway aprons when themotor vehicle is driven on public roads.

Consistent with the above description, a method is also provided whichnot only reduces the overall weight of the rear differential coolingsystem but also improves weight distribution in a motor vehicle equippedwith a front mounted engine. Improved handling and race trackperformance is a consequence of these benefits.

The method may be generally described as including the steps of: a)mounting a rear differential heat exchanger 38 motor vehicle rearward ofa rear differential 42 of the motor vehicle, (b) directing air throughan air inlet 16, 18 in a rear diffuser 12 of the motor vehicle and thenthrough the rear differential heat exchanger, and (c) exhausting ordischarging that air through a rear valance 32 of the motor vehicle. Insome embodiments, the method further includes the step of delivering theair from the air inlet 16, 18 to the rear differential heat exchanger 38by means of an air tunnel 24, 26. In addition, the method may includethe step of increasing a cross-sectional area of the air tunnel 24, 26as the air tunnel approaches the rear differential heat exchanger 38.

The foregoing has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theembodiments to the precise form disclosed. Obvious modifications andvariations are possible in light of the above teachings. For example,while not illustrated, it should be appreciated that the air being drawnthrough the first and second air inlets of 16, 18 and the first andsecond air tunnels 24, 26 may also be utilized to cool other operatingcomponents of the motor vehicle rearward of the rear differential 42 ifdesired. All such modifications and variations are within the scope ofthe appended claims when interpreted in accordance with the breadth towhich they are fairly, legally and equitably entitled.

What is claimed:
 1. A body panel system for a motor vehicle, comprising:a rear diffuser including a first air inlet and a second air inlet; anunderbody panel overlying said rear diffuser; a first air tunnel formedbetween said rear diffuser and said underbody panel, said first airtunnel extending from said first air inlet to a first air tunnel outletabove said rear diffuser; a second air tunnel formed between said reardiffuser and said underbody panel, said second air tunnel extending fromsaid second air inlet to a second air tunnel outlet above said reardiffuser; a rear valance including a first vent opening and a secondvent opening discharging air received from said first air tunnel andsaid second air tunnel; and a heat exchanger providing cooling to a reardifferential of said motor vehicle wherein said heat exchanger isprovided between (a) said first vent opening and said second ventopening and (b) said first air tunnel outlet and said second air tunneloutlet.
 2. The body panel system of claim 1, wherein said first ventopening and said second vent opening are spaced from said first airtunnel outlet and said second air tunnel outlet.
 3. The body panelsystem of claim 2, wherein said heat exchanger is provided over saidfirst air tunnel outlet and said second air tunnel outlet.
 4. The bodypanel system of claim 3, wherein said first vent opening is aligned withsaid first air tunnel outlet and said second vent opening is alignedwith said second air tunnel outlet.
 5. The body panel system of claim 4,wherein said first air tunnel has a first cross-sectional area A₁ atsaid first air inlet and a second cross-sectional A₂ at said first airtunnel outlet and said second air tunnel has a third cross-sectionalarea A₃ at said second air inlet and a fourth cross-sectional area A₄ atsaid second air tunnel outlet where A₁<A₂ and A₃<A₄.